This invention relates to direct reduced iron (DRI), more particularly, to the process, method and apparatus for the production of direct reduced iron and/or pig iron from iron ores having a high-phosphorus content. The method and apparatus according to this invention provide an effective process for reducing phosphorus in iron ores, making them suitable for use in processes for the direct reduction of iron ores. The low-phosphorus content iron ore can be used in steel making, for instance the ore can be used as a raw material in electric arc steelmaking process or may be melted down to produce pig iron in electric reducing or cupola furnaces.
The direct reduction of iron oxide in forms, such as lumps or pieces of variable ore particle sizes, to metallic iron in the solid state has become a commercial reality throughout the world in the last thirty years. The combined annual capacity of the direct reduction plants currently in operation exceeds fifty million metric tons of direct reduced iron. DRI is mainly used as a raw material for the manufacture of steel in electric arc furnaces. It is expected that the world demand for direct reduced iron will increase substantially over the next few years as additional electric arc furnace steel manufacturing plants are built.
There are difficulties associated in the removal of phosphorus from the iron oxide matrix. Many of the same process for the concentration of iron also concentrate phosphorus. Known processes for the direct reduction of iron oxide to metallic iron start with iron ore and/or ore lumps having a predetermined phosphorus content of less than or about 0.05%. Since phosphorus is directly associated with iron in the iron ore matrix, iron ore with concentrations of phosphorus greater than about 0.05% are unsuitable for the production of direct reduced iron. As a result, large stockpiles of crude iron ore with a high-phosphorus content and a high total iron content accumulate at ore working sites and cannot be delivered. The difficulty in separating phosphorus from the crude iron ore creates large reserves of crude iron ore that cannot be used to produce steel in electric steel making furnaces and/or pig iron furnaces.